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lazlo
10-24-2007, 04:36 PM
About a month ago I stumbled across a 23 lb spool of Ampco Aluminum Bronze MIG wire on Ebay:

http://i7.ebayimg.com/04/i/000/b9/8d/69f4_1.JPG

Aluminum Bronze has a tensile strength of 80,000 - 105,000 PSI (mild steel is 60,000), and a Rockwell Hardness of 80 - 100 HrB (mild steel is 71 HrB).
So it's extremely wear resistant, but it still has the bearing properties (low-friction, anti-galling) of SAE 660 bearing bronze.

I was playing around in the shop to see if I could use the Aluminum Bronze to re-surface cast iron with MIG Brazing: i.e., using the MIG gun to "spray" a coating of aluminum bronze on the cast iron substrate, without overheating the cast iron itself.

This is just a quick and dirty "hardfacing" pass: I didn't overlap passes like you do with real hardfacing. This is a ductile iron casting from an old drill press quill:

http://i164.photobucket.com/albums/u15/rtgeorge_album/ABHardface001s.jpg

The iron casting never got above ~400 F, but the bronze is completely bonded to the surface, as you can see after a couple of milling passes with a cheap 2" Chicom TPG insert facemill (aluminum bronze is a bitch to mill!). The mill is running on powerfeed in this picture, but the camera stopped the motion:

http://i164.photobucket.com/albums/u15/rtgeorge_album/ABHardface009s.jpg

And here's the final result. It's hard to see from the shiny reflection of the bronze, but there's no porosity, aside from the uneven passes on the far side with the MIG gun (which is why they tell you to do overlapping passes with hardfacing):

http://i164.photobucket.com/albums/u15/rtgeorge_album/ABHardface011s.jpg

Now I'm looking around the shop for parts that need a low-friction, highly wear-resistant coating :)

I've got an extra set of half nuts for my lathe that were badly worn -- a couple layers of aluminum bronze and an ACME tap, and I'll have a new set of low-friction, extremely wear-resistant, half nuts.

I've also got a mis-matched tailstock for my T&C Grinder that's 1/8" low from the workhead -- I'm thinking of facing the bottom with aluminum bronze, and some mill and hand-scraping work...

pcarpenter
10-24-2007, 04:48 PM
I would guess you are not going to like hand scraping that stuff:D

It may not be an issue with a TS for a tool and cutter grinder (unlike say a lathe tailstock) but the trouble with way faces with dramatically different hardness is that you move almost all the wear to the softer surface. You might not want to do this on a lathe tailstock for example. Lest anyone would misinterpret what I am saying, hard on soft is a good idea for way faces...but *really* hard on soft means most of the wear on one face.

Bridgeport in recent years hard chromes the knee way faces (horizontal) while the mating face on the bottom of the saddle remains soft--another example of a dramatic difference in surface hardness on ways. This is not a bad way to go in that application since the saddle is smaller than the knee. It reduces the age-old problem of wearing a low place in the larger surface from moving the saddle in a limited area. On the other hand, the saddle should wear evenly across its whole surface since it is the smaller surface and moves entirely within the bounds of the knee ways.....but I digress.

How about using it for more traditional hard facing applications like wear edges on plows? It ought to slide better.

paul

oldtiffie
10-24-2007, 05:49 PM
About a month ago I stumbled across a 23 lb spool of Ampco Aluminum Bronze MIG wire on Ebay:

http://i7.ebayimg.com/04/i/000/b9/8d/69f4_1.JPG

Aluminum Bronze has a tensile strength of 80,000 - 105,000 PSI (mild steel is 60,000), and a Rockwell Hardness of 80 - 100 HrB (mild steel is 71 HrB).
So it's extremely wear resistant, but it still has the bearing properties (low-friction, anti-galling) of SAE 660 bearing bronze.

I was playing around in the shop to see if I could use the Aluminum Bronze to re-surface cast iron with MIG Brazing: i.e., using the MIG gun to "spray" a coating of aluminum bronze on the cast iron substrate, without overheating the cast iron itself.

This is just a quick and dirty "hardfacing" pass: I didn't overlap passes like you do with real hardfacing. This is a ductile iron casting from an old drill press quill:

.............................
..............................

The iron casting never got above ~400 F, but the bronze is completely bonded to the surface, as you can see after a couple of milling passes with a cheap 2" Chicom TPG insert facemill (aluminum bronze is a bitch to mill!). The mill is running on powerfeed in this picture, but the camera stopped the motion:

.............................
...........................

And here's the final result. It's hard to see from the shiny reflection of the bronze, but there's no porosity, aside from the uneven passes on the far side with the MIG gun (which is why they tell you to do overlapping passes with hardfacing):

...................................
.....................................

Now I'm looking around the shop for parts that need a low-friction, highly wear-resistant coating :)

I've got an extra set of half nuts for my lathe that were badly worn -- a couple layers of aluminum bronze and an ACME tap, and I'll have a new set of low-friction, extremely wear-resistant, half nuts.

I've also got a mis-matched tailstock for my T&C Grinder that's 1/8" low from the workhead -- I'm thinking of facing the bottom with aluminum bronze, and some mill and hand-scraping work...

Good post lazlo.

MIG is or can be a "spray" (or "drop") transfer process - depending on settings and "gas" used.

I'd reckon that that "hand-scraping" will be a bit "tedious" but if the finish is "fine" and "true" enough in the "as machined" state then perhaps it might not be necessary on a T&C TS base - but it sure would enhance the "look" and "slipperiness" though.

Can't query (or better) the material "cost" though.

I guess that in theory at least it should be quite possible to use that MIG wire as a filler rod for TIG as well.

neonman
10-24-2007, 06:30 PM
Lazlo, great post. This appears to be a good way to make repairs on some types of C.I. applications.

I have an antique engine with somw very serious pitting in part of the cylinder. I was wondering if you think this would be a way to repair it. The pitting covers a square inch or so, and is about 1/16 deep at the worst spot.

neonman

BTW, I'm just north of you, in Leander.

lazlo
10-24-2007, 06:57 PM
I would guess you are not going to like hand scraping that stuff:D

Yeah, no kidding :) I'm going to try scraping it tonight. Holding it is going to be a pain (unless I make a triangular jig) -- I might just stick it on a magnetic chuck...


You might not want to do this on a lathe tailstock for example.

That was one of the first things I thought of: building-up the base of a worn lathe tailstock. Wear issues aside, the bottom of the tailstock probably wouldn't be a good application for a slippery bronze surface -- I saw a post from a guy who make a carriage stop out of bronze, and it was so slippery on the cast iron ways that it wouldn't stick. I'd be concerned that bronze on the tailstock base would make it slide around too easily. Maybe one of the luminaries here could comment on that...


It may not be an issue with a TS for a tool and cutter grinder (unlike say a lathe tailstock) but the trouble with way faces with dramatically different hardness is that you move almost all the wear to the softer surface.
...
Lest anyone would misinterpret what I am saying, hard on soft is a good idea for way faces...but *really* hard on soft means most of the wear on one face.

I always wondered about that Paul -- the principal of a lap is that you rub a hard and soft material together, and the lapping grit embeds into the softer material, and wears the harder material. So if you have hard chrome on cast iron, like a Bridgeport way, or aluminum bronze on cast iron, shouldn't the grit embed in the cast iron way, and wear the hard chrome, or aluminum bronze? Or if you made a gib strip out of aluminum bronze (which would have lower friction), would the cast iron dovetail preferentially wear the aluminum bronze?

Anchor Bronze sells aluminum bronze "wear plates" -- steel strips that are electroplated with aluminum bronze, and meant as slide plates for box ways. But the aluminum bronze plates have graphite plugs for lubrication, and they don't mention what the mating material is:

http://www.anchorbronze.com/finishedwearplates.htm

http://www.anchorbronze.com/wearplate.jpg


How about using it for more traditional hard facing applications like wear edges on plows? It ought to slide better.

I imagine it would work great for a plow -- the problem is, I don't have one :D

Seriously though, now that I know that I can "squirt" the aluminum bronze, I want to try some more traditional cast iron brazing repairs, but using the MIG gun with aluminum bronze instead of a torch and brazing rod. I'm curious if the aluminum bronze will wick into the crack like it does with oxy -- I'm guessing not...

lazlo
10-24-2007, 07:07 PM
Good post lazlo.

MIG is or can be a "spray" (or "drop") transfer process - depending on settings and "gas" used.

Thanks Tiffie. To clarify, I wasn't doing MIG spray transfer -- sorry about the abuse of that welding term. It's hard to describe, but when you pull the trigger on the MIG gun, the bronze just "squirts" out and flows almost like water, not like the little droplets you get when you're MIG'ing with traditional mild steel filler wire.


I'd reckon that that "hand-scraping" will be a bit "tedious" but if the finish is "fine" and "true" enough in the "as machined" state then perhaps it might not be necessary on a T&C TS base - but it sure would enhance the "look" and "slipperiness" though.

The milled surface was OK, but I didn't want to use a good facemill on it until I figured out that it was worth trying. Now that I know that it works, I have a Sandvik high positive "shear mill" (45 lead angle) that should give a really nice finish. But I'm also going to have to learn how to do the overlapping hardfacing patterns -- you really need a uniform thickness on the aluminum bronze to mill it down flat. You can see where I duffed that on the far edge of the casting in the third picture: the cast iron is showing through...


I guess that in theory at least it should be quite possible to use that MIG wire as a filler rod for TIG as well.

I did that last weekend when I first got the spool :) The spool had been sitting around in someone's house for years, and I had to cut off a bunch of the wire getting it to feed the first time. I used some of it to TIG copper plate. Stupid welding tricks :)

By the way, a friend asked by email whether it weld mild steel. Yes, it does, but the steel has to be clean. We tried MIG'ing it to steel I-Beam, which is covered with that impenetrable red paint, and the aluminum bronze would just ball up, and then the electrode would explode. It would leave a bright green and black poof on the steel (from the copper content), somewhat like the subtractive color version of the orange and black poof you get when you vaporize a TIG electrode :)

wierdscience
10-24-2007, 07:44 PM
Cool!I like a lot,wheels are turning already(never mind the smoke):D

Okay,you proved it works for build ups,now how about an experiment?

Have you tried Joiningtwo pieces of cast together?An inquiring mind wants to know:D

torker
10-24-2007, 08:01 PM
Laz..Thanks for the info! I've never used that filler before and I'd like to see what else you could dream up for it.
Looks like it'd be a good additon to have in my welding shop.
Russ

Spin Doctor
10-24-2007, 08:11 PM
Where I used to work before I retired we had both brass and Ampco rod available in the weld shop. We practically never used Ampco rod on CI. Would cause to many problems in the remachining phase. One of the welders if he wanted to mess with the apprentices would drop some aluminum in the brass being used to braze the CI back together (sometimes it seemed like the parts weren't in the same room by the time you got done prep grinding). Things would be going along great until you hit a spot harder than hades

Willy
10-25-2007, 01:41 AM
Interesting post Lazlo, always wanted to get my hands on spool of that myself and see what I could come up with. Have fun with the experiments and keep us posted on some of the projects and applications you come up with.

As far as snow plow blades goes, I think it will be hard to compete with carbide inserts as far as wear and longevity goes. I've used conventional and carbide insert type blades in winter highway maintenance applications, and carbide blades used on pavement will outlast regular blades 20:1 .

But yeah, rub it in, you don't have any of that white sh*t to worry about.:D

chipmaker4130
10-25-2007, 02:32 AM
Lazlo, what shield gas did you use?
Thanks,
Gordon

oldtiffie
10-25-2007, 07:42 AM
Lazlo,

why not just use "wear plates" or similar (as you posted earlier) on your T&C TS base. At least all the joints are "Cold/mechanical" and with no heat applied.

Even with the best will in the world and "best guess" there is no dead-certainty of knowing where or how the heat will show up and what effects it might have.

lazlo
10-26-2007, 11:32 PM
Lazlo, what shield gas did you use?

Hi Chip,

I used 75/25, which worked fine, but was a little hot. AMPCO's AWS sheet recommends 75/25 or pure argon, suggesting that the latter would be better.

Unfortunately, our welding stalls at ACC are setup so the big MIG welders have 75/25 cylinders in the stall with the welders, so I can't easily move bottles around, but when I buy a TIG next month, I'll have a argon bottle next to a 75/25 bottle, so I'll be able to try both.

Cheers,

Robert

lazlo
10-26-2007, 11:33 PM
why not just use "wear plates" or similar (as you posted earlier) on your T&C TS base. At least all the joints are "Cold/mechanical" and with no heat applied.

Those Anchor Bronze "Lamina" wear plates that I linked are unGodly expensive. But I did think about just planning a sheet of cast iron down to 1/8" thickness, and bolting it on (or maybe silver soldering it.

oldtiffie
10-27-2007, 02:30 AM
Those Anchor Bronze "Lamina" wear plates that I linked are unGodly expensive. But I did think about just planning a sheet of cast iron down to 1/8" thickness, and bolting it on (or maybe silver soldering it.

Hi laslo.

Seems reasonable re "Lamina" plates.

But as it is static for all intents and purposes, why not just use brass strips and screw or adhere them.

Fly-cut to size and perhaps hand-scrape or just use a round-nose hand-chisel and cut in serpentine lubrication grooves. Or if you have lots of time (to waste?) - combine both.

Hope it helps.

Orrin
10-27-2007, 09:07 AM
I've got an extra set of half nuts for my lathe that were badly worn -- a couple layers of aluminum bronze and an ACME tap, and I'll have a new set of low-friction, extremely wear-resistant, half nuts.

I've never worked with aluminum bronze, but I've been told it is very difficult to machine. Do you think an acme tap would even touch it?

Dunno. Just askin'.

Orrin